What you you say would be the best locker or posi to install in a dana 30. I drive all year and there is 7 months of ice and snow on the road. I want something that when put in 4x4 won't send me or the wife shooting for the ditch when put in the big wheel. As well as easy to steer, but good performance.  

A replacement automatic locker would be last choice for ice and snow big time. Even a posi will be a bit iffy at times but better than a locker. The best setup in locker world would be a manually selectable locker. Best possible solution (if legal where you are) is studded snow tires in winter. You would keep rear end behind you and keep it from wanting to pass you. My wife has a stripped down 2000 2wd Cherokee with a 2.5 and a 5 speed. Been running studded tires on rear in winter since second winter after we got it new. It is a tank in snow and ice with tires and about 100 pounds of ballast too. If has never failed to get wife home safely from work under the worst of conditions with no surprises and she does not worry about it at all (first winter scared her) A few times it has had her coworkers (she is a teacher) scratching their heads because they have taken a few trips to ditch with 4x4 grand Cherokees in 4wd on bad days and she just keeps plugging a long with no white knuckles. You have to run them to appreciate what they can do as it will easily pull away from a 4x4 model on ice that is stud-less and with no tendency to trade ends either. Stops straight too because studs on rear axle keep it back there.